According to researches, manual knitting apparatus were developed during the fourth and fifth centuries for knitting knitted fabrics manually. Since the Industrial Revolution, various mechanical knitting machines were developed and intensively used to replace conventional manual knitting apparatus. In 1816, Marc Brunnel invented a sinker wheel machine using sinkers to match with needles in knitting knitted fabrics. Nowadays, most automatic knitting machines use sinkers to hold the fabric and the yarns, and knitting needles are reciprocated vertically to hook up or release the yarns while sinkers are reciprocated horizontally. Therefore, the design of the sinkers in a knitting machine has concern with the quality and pattern of the knitted fabric. However, because regular knitting machines use only one sinker in one knitting slot, the sinkers of the knitting machines cannot positively hold down the fabric and the yarns. For example, a towelling is made by knitting a base yarn and a face yarn in each knitting slot, and the respective sinker is operated to hold down the fabric and the face yarn only, therefore the base yarn tends to float, causing a different color of yarn shown on the surface of the fabric. Furthermore, different sinkers may be used for knitting face-loop towelings and reverse-loop towelings. However, one a knitting machine is to be changed from the face-loop knitting to the reverse-loop knitting, the sinkers and sinker plate holder as well as parts of the machine must be changed or modified. Besides, these sinkers do not allow the machines to knit a cutting motif towelling of two or more colors. Besides, the knitting of a jacquard fabric is performed by means of the operation of specific jacquard sinkers, however, these jacquard sinkers cannot be replaced by the aforesaid sinkers for face-loop or reverse-loop knitting.
FIG. 1 shows a sinker for knitting machines according to the prior art. The sinker comprises a throat 10 for retaining the fabric, a nose 20, which holds down the fabric during the up stroke of the knitting needle, a flank 30, which forces the (face) yarn into a new loop during the down stroke of the knitting needle, and a sinker butt 40, which is moved in the respective sinker slot in the sinker plate holder. As the sinker can only hold down the face yarn, the base yarn will displace during the knitting operation. Furthermore, the sinker allows the knitting needle to knit face loops only.